Device for installing and removing big-end caps of connecting rods on internal combustion engines

ABSTRACT

A device for installing and removing connecting rod big-end caps on internal combustion engines, comprising: a supporting frame mounted on one side and horizontally movable lengthwise of the engine; a first carriage mounted on the frame and displaceable transversely thereof and horizontally at right angles to the displacement thereof; a second carriage mounted on the first one and movable thereon at right angles to the joint interface between cap and connecting rod in a given position of the latter; a toggle system movable in a vertical plane and pivoted with one end to the second carriage while being provided at the other end with connecting rod big-end cap-holding means; and actuating power means for operating at least said toggle system.

United States Patent Bouquet May 27, 1975 [54] DEVICE FOR INSTALLING AND 3.520.045 7/l970 Kiihn 29/200 P REMOVING BIG END CAPS OF 3,8l3,755 6/l974 Maskell et al. 29/252 CONNECTING RODS ON INTERNAL FOREIGN PATENTS OR APPLICATIONS COMBUSTION ENGINES 1959,441 6/1970 Germany 29/200 R J can-C laude Bouquet, Pantin, France Societe dEtudes de Machines Thermiques, Saint-Denis, France Filed: Oct. 3, 1974 Appl. No.: 511,679

Inventor:

Assignee:

Foreign Application Priority Data Nov. 9, l973 France 73.39988 References Cited UNITED STATES PATENTS Paxman 29/200 R Carlson 29/252 Primary Examiner-Donald G. Kelly Assistant ExaminerHarold P. Smith, Jr.

[57] ABSTRACT A device for installing and removing connecting rod big-end caps on internal combustion engines, comprising: a supporting frame mounted on one side and horizontally movable lengthwise of the engine; a first carriage mounted on the frame and displaceable transversely thereof and horizontally at right angles to the displacement thereof; a second carriage mounted on the first one and movable thereon at right angles to the joint interface between cap and connecting rod in a given position of the latter; a toggle system movable in a vertical plane and pivoted with one end to the second carriage while being provided at the other end with connecting rod big-end cap-holding means; and actuating power means for operating at least said toggle system.

16 Claims, 6 Drawing Figures PIJENIEQ 1W2 71975 SHEET 0 3 [IF PMENTEB W 2 7 I975 SHEET 0 0F PATENTEU W2 7 I975 88:75 290 SHEET CSSF 5 DEVICE FOR INSTALLING ANI) REMOVING BIG-END CAPS OF CONNECTING RODS N INTERNAL COMBUSTION ENGINES The present invention relates essentially to a device for installing and removing the big-end caps of connecting rods on internal combustion engines of relatively large size such as for instance a marine propulsion or ship powering or driving engine or an engine of a stationary plant. This process is adaptable irrespective of the kind of connecting rod big-end (i.e. whether the joint face between cap and connecting rod extends at right angles to or slantwise with respect to the con necting rod centre line).

On such engines the connecting rod big-end caps are very heavy and it is therefore difficult to handle them, The installing and removing of these caps on or from the connecting rod big-ends is presently carried out by hand with rudimentary handling means and it is necessary to pass the cap through an opening of the engine crank ease for bringing it into aligned registering relationship with the connecting rod big-end and then it is necessary to insert the fastening anchor or tie bolts into the corresponding cap openings accommodating them and finally to screw the nuts on the tie bolts with a given tightening pressure or clamping stress. The removal ofthese caps which has to be effected for inspection and replacement of the bearings or bushings of the connecting rod big-end as well as for the inspection of the pistons is carried out according to the same operating steps effected in the reverse order of succession or sequence so that a removal and a refitting of these caps onto the connecting rod big-ends take a long time, are of delicate character and require much labour or workmanship.

In order to avoid these inconveniences the invention provides a device for installing and removing connecting rod big-end caps on internal combustion engines, which is characterized in that it comprises: a supporting frame adapted to be mounted on the sides of the engine and horizontally movable along the engine over at least one part of the length of the latter; a first carriage mounted on said supporting frame and displaceable transversely of the latter in a horizontal direction perpendicular to the path of travel of the supporting frame; a second carriage mounted on the first carriage and displaceable on the latter in a direction perpendicular to the joint interface plane between the cap and the connecting rod in a given position of the latter; a toggle system or like arrangement of linked arms or pivotally interconnected levers displaceable in a substantially vertical plane and pivotally connected with one end thereof to said second carriage while comprising at the other end holding means for supporting or backing the connecting rod big-end cap; and for instance hydraulically operated servo-control or like actuator means for operating at least said toggle system.

The device according to the invention thus enables a convenient handling of the connecting rod caps which may be loaded on or unloaded from the device at one end of the engine and then brought into aligned registering relationship with the corresponding connecting rod big-end and then moved or fitted into proper position onto the connecting rod big-end before being fastened or secured thereto.

According to a further characterizing feature of the invention said toggle system comprises at its connecting rod big-end cap-holding end actuators for tensioning the cap-fastening anchor or tie bolts, said actuators comprising each one a pair of overlying or stepped hollow cylindrical pistons through which extends a rod the bottom end of which is formed with a screw-threaded blind hole which may be screwed onto the correspond ing end of said tie bolt and the head of which, projecting outwards from the actuator, is screw threaded and provided with a nut bearing upon the outer face of one aforesaid piston.

Thus the device according to the invention also enables to fasten the caps onto the connecting rod bigends by means of said anchor or tie bolts and nuts, the nuts being screw threaded onto the tie bolts with a given clamping stress or tightening pressure. As the tie bolts are tensioned by said actuators of the cap holder the tightening of the nuts onto the fastening tie bolts is carried out without the least difficulty. Moreover, the clamping stress or tightening pressure obtained is always uniform.

It is thus seen that the device according to the inven tion enables to achieve a substantial time saving for installing and removing the connecting rod big-end caps, that it enables to save a substantial labour or workman ship and that it moreover greatly facilitates the fastening of the caps onto the connecting rod big-ends.

The invention will be better understood and further objects. characterizing features, details and advantages thereof will appear more clearly as the following explanatory description proceeds with reference to the accompanying diagrammatic drawings given by way of non-limiting example only illustrating a presently preferred embodiment of the invention and wherein:

FIG. 1 is a side view with parts broken away showing the device according to the invention with the toggle system being in retracted position or connecting rod big-end cap transport position;

FIG. 2 is a view similar to FIG. 1 but showing the toggle system in extended condition and a cap ready to be mounted on a connecting rod big-end;

HO. 3 is an end view seen in the direction of the arrow III in FIG. 1',

FIG. 4 is a partial cross-sectional view showing the servo-control power means or actuators and the gears of the toggle system; and

FIGS. 5 and 6 are a bottom view and a longitudinal sectional view, respectively, of a power ram actuator for tensioning a tie bolt for fastening a cap on a connecting rod big-end.

The device according to the invention for installing and removing connecting rod big-end caps on an internal combustion engine comprises a supporting frame 1 which is mounted for translatory motion along the engine over at least one portion thereof and advantageously beyond one end of the engine by means of rails or like tracks or runways 2 and 3 secured alongside of the engine at the bottom and at the top. respectively. thereof. The rails 2 and 3 are extended to the forward end of the engine in order to enable the mounting and positioning of the device and on the other hand to enable the removal and withdrawal of the connecting rod caps on the device. The corresponding portions of the supporting frame 1 comprise brackets 4 on which are mounted guide rollers 5 cooperating with the runways consisting of the rails 2 and 3 and the upper brackets 4 also carry supporting rollers 6 bearing on the base of the runway. This supporting frame 1 consists of a pair of vertical side webs 7 which are braced at their upper and lower portions. These vertical webs or plates 7 are provided on their outside face with handles or like hand-grips 8 enabling to move the whole assembly by hand according to a translatory motion.

Horizontal rails 10 are secured onto the inside faces of the vertical webs or plates 7 onto the top edges thereof and are directed to extend at right angles to the longitudinal rails 2 and 3. These rails 10 form runways for four pairs of pivoted rollers 11 connected to a pair of vertical plates 12 extending in parallel relation to the web 7 and interconnected in bracing relationship to form a first carriage l3 movable for translatory motion in a direction perpendicular to the direction of travel of the supporting frame 1. Resilient stop means 14 are provided at each end of the rails 10 and limit the displacement of the first carriage 13 in either direction.

The vertical plates 12 comprise each one a pair of apertures of elongated shape 15 which extend slantwise in parallel relation to the direction perpendicular to the joint interface plane between a cap and an associated connecting rod big-end when the corresponding connecting rod is in a predetermined position. The centre line of the connecting rod in this position is shown at 16 in FIGS. 1 and 2 whereas the joint interface plane is represented by the straight line 17 and the line perpendicular to this joint interface plane is shown at 18.

A second movable carriage 20 consists of a box-like casing both lateral sides of which extend in parallel relation to the vertical plates 12 and are each one connected to two running and guiding rollers 21 engaging said apertures 15. The second movable carriage 20 is therefore displaceable in parallel relation to said axis 18. Its displacement is carried out by means of a hydraulically operated linear power ram actuator the cylinder 22 of which is pivotally connected to the bottom lower portion of said first movable carriage 13 whereas the piston rod 23 of which is mounted on a yoke or clevis 24 integral with the box-like structure or casing of the second movable carriage 20. A handle 25 integral with the yoke or clevis 26 mounting the cylinder 22 on the first movable carriage l3 enables to displace this first carriage by hand.

The second movable carriage 20 comprises inside of said box-like casing a hydraulically operated rotary power means or actuator 30 the output shaft 31 of which carries a gear 32 secured through keys 29 to the shaft 31. The gear 32 meshes with a gear 33 secured to and rotatable with the end of a splined shaft 34 extending in parallel relation to the shaft 3! and the opposite end of which is connected to a gear 35 for rotation therewith. This end of the shaft 34 is rotatably mounted within a clevis or like bracket 36 secured to the boxlike casing 20 and projecting outwards therefrom. That portion of the bracket 36 outside of the box-like casing 20 which is directed towards the internal combustion engine is integral with a splined shaft 37 on which a toothed segment or like sector gear 38 is mounted and held against rotation. This toothed segment 38 is therefore stationary or held against rotation on the boxlike casing 20 through the medium of the shaft 37 and bracket 36.

A first linked arm consists of a fully closed small casing 39 one end of which is integral with a toothed segment or like sector gear 40 which meshes with said gear 35 mounted inside of the second movable carriage 20. The casing 39 forming the first arm is pivotally mounted through bearings 41 onto the gear 38 integral with the bracket or clevis 36 and it comprises on its central or intermediate portion a shaft 42 on which an idle or loose gear 43 is seated for free rotation. This gear 43 is on the one hand in meshing engagement with the toothed segment 38 mounted to be integral and rotatable with the second movable carriage 20 and on the other hand in meshing engagement with a gear 44 mounted for rigid connection and rotatable with a splined shaft 45 carried by a clevis or bracket 46 forming a second linked or pivoted arm. The corresponding end of the casing 39 forming the first linked or pivoted arm is pivotally mounted for swinging about the gear 44 by means of bearings 47.

At its free end the second linked or pivoted arm con sisting of a clevis or yoke 46 is rigidly connected to a member 84 seen in FIGS. 1 and 2 and which forms a holder for a connecting rod cap 48. The top face of the member 84 has a shape which is complementary of or mating with that of the bottom face of the connecting rod cap and comprises hollow cylindrical parts 49 described with more details in FIGS. 6 and 5, in which are received the anchor bolts or tie bolts 50 for fastening the cap 48 onto the connecting rod big-end 51 and which also comprise hydraulically operating actuators or like power rams for tensioning the tie bolts 50.

Reference should now be made to FIGS. 6 and 5 for the description of these tensioning power ram actuators.

The cylindrical elements 49 consist of a first hollow cylindrical portion 52 on the lower end of which is secured a cylinder 53 of a hydraulically operated power rarn actuator. Each cylinder 53 is formed with a screwtnreaded port 54 to which may be connected a duct or like pipe-line for feeding hydraulic pressure fluid. Each hydraulically operated actuator comprises a pair of overlying pistons 55 and 56, respectively, which are hollow and cylindrical and through which extends a rod 57 the foot or bottom portion of which is formed with a screw-threaded central blind hole 58 which is threadingly engaged by the end of a tie bolt 50. The head of the rod 57 which projects outwards from and to the outside of the cylinder 53 is screw threaded and receives a cottared or pinned nut 59 having a bearing face 60 co-operating with a corresponding seat constituted by the outer end of the second piston 56.

The piston 56 is formed with a cylindrical section 61 which is movable within a cylindrical shoulder 62 of the cylinder 53 the top end of this cylindrical section or sleeve-like hub 61 bearing against or being engageable with the head of the piston 55. The latter is formed with a cylindrical section or sleeve-like hub 63 movable within the end opening of said part 52 and a first cylinder chamber is defined between the head of the piston 55 and the end of the part 52. A second cylinder chamber is defined in the same manner between the head of the piston 56 and the shoulder 62 of the cylinder 53. Both of these cylinder chambers are connected through ducts or like passageways 65 and 66, respectively, to the inlet port 54 for feeding hydraulic pressure fluid thereto. The top end of the cylindrical section or sleeve-like hub 61 of the second piston 56 comprises a ring-shaped stop member or abutment 67 and disk springs or like spring washers 68 are fitted between this abutment 67 and the shoulder 62 of the cylinder 53. Thus the pistons 55 and 56 assume at rest the positions shown in FIG. 6.

Through the top end of the portion 52 of the cylindrical element 49 which has just been described extends the anchor bolt or tie bolt 50 and it is dimensioned so as to be able to receive a nut 70 for fastening the cap onto the connecting rod big-end. The nut 66 comprises on its periphery blind holes or recesses 71 which enable to screw it by means of a tommy-bar 72 from the outside of the cylindrical element 49, the tommy-bar 72 extending through an annular aperture 73 of the wall of the element 52.

The device according to the invention further comprises for instance hydraulically operated servo-control means or power actuators for operating the toggle system and for feeding hydraulic power ram actuators for tensioning the tie bolts 50. These servo-control means are mounted on the supporting frame 1 at the lower portion thereof and comprise an electrical motor 80 associated with a hydraulic pump 81, a hydraulic fluid tank 82 and an electrical control cabinet 83 (FIGS. 1 and 3). The hydraulic pump comprises an output pres sure multiplier and feeds on the one hand directly the rotary actuator 30 mounted on said second movable carriage 20 and on the other hand through the medium of the pressure multiplier both actuators for tensioning the tie bolts 50 for fastening the caps onto the connecting rod big-ends.

The operation of the device just described is the following:

For installing a connecting rod big-end cap, the supporting frame 1 is moved until abutting engagement with the front ends of the rails 2 and 3 and it is locked or held against motion in this position by means of a manual lock caused to engage machined notches provided in the upper runway rail 3. The first movable carriage 13 is moved until abutment against the ends of the rails located towards the engine axis and it is locked or held against motion in this position by means of a manual latch enabling to lock this first movable carriage on the rails 10 in both of these end positions. The second movable carriage is in the lower position on the first movable carriage 13 i.e. the running rollers 21 are bearing on the bottom ends of the guide apertures 15. Said loading arms 39 and 46 are in the positions shown in FIG. 1 so that the supporting member 84 is horizontal. For putting a connecting rod cap 48 onto the supporting member 84 both fastening nuts 70 are removed inside of the cylindrical elements 48 of the supporting member 84. Then the connecting rod cap is laid on the supporting part 84. The movable carriage 13 is then unlocked and then moved back on the rails 10 and brought to the rear position shown in phantom lines in FIG. 1. It is then locked in this position by said hand-operated latch.

The supporting frame 1 is unlocked and is then positioned by means of the handles 8 in registering relation to the desired cylinder i.e. in front of an inspection hole 75 provided in the wall of the internal combustion engine case and corresponding to the connecting rod on the big-end of which the cap 48 is to be fitted. In this position the supporting frame 1 is locked or held against motion by means of said hand-operated latch which engages the notches of the upper rail 3. The first movable carriage 13 is then unlocked and then moved to the forward position as shown in FIG. 1 so that the supporting part 84 and the connecting rod big-end cap 48 partially engage the inspection hole 75. The first movable carriage 13 is then locked or hcld against motion in this position. Said servo-control actuator means 80, 81 and 82 are then energized and the rotary actuator 30 of the second movable carriage 20 is supplied with pressure fluid directly from the hydraulic pump 81. The first linked arm 39 is caused to tilt or to rock at the same time as the second linked arm 46 so that the connecting rod big-end cap 48 is moved into the position shown in FIG. 2. The hydraulically operated linear actuator or power ram 22 is fed with pressure fluid so that the second movable carriage 20 is displaced in parallel relation to the axis 18 until the connecting rod cap 48 is brought in engagement with the joint interface plane of the connecting rod big-end 51.

Then, on the cylindrical elements 49 of the supporting member 84 the yoke-like retaining clips or clamps 76 are caused to swing into position for keeping said rods 57 in place. These rods move downwards and the anchor bolts 50 are then allowed to move downwards within said first portion 52 of the cylindrical element 49.

The nuts are screw threaded by means of the tommy-bar 72 onto the anchor bolts and the rods 57 are then moved upwards and screw threaded onto the bottom end of the anchor bolts 50 as shown in FIG. 6.

The tensioning power ram actuators are then pressurized or energized i.e. hydraulic pressure fluid is fed to the port 54 of said cylinder 53. The nuts 70 are then thoroughly tightened onto the anchor bolts 50 by means of the tommy-bar 72 and the pressure is then released in the tensioning actuators. The rods 57 are then unscrewed and the supply of the linear actuator 22 with hydraulic fluid is acted upon for returning said second movable carriage 20 to its bottom lower position while the cap 48 remains secured onto the connecting rod big-end 51. The rods 57 are then mounted within the cylindrical elements 49 and retained in position by the yoke-like clamps or clips 76. The feeding of the rotary actuator 30 with hydraulic fluid is then acted upon in order to bring both linked arms 39 and 46 back to the positions shown in FIG. 1. Said servo-control actuators or motors are then stopped, the first movable carriage 13 is unlocked and moved into the rear position shown in phantom lines in FIG. 1 where it is locked again against motion and then the supporting frame 1 is unlocked and moved to the loading station located forward of the internal combustion engine. The movable carriage 13 is then unlocked and then moved to the forward end of the supporting frame 1 where it is locked again against motion. The whole assembly is then ready to receive a new connecting rod big-end cap.

From the previous description it is readily appreciated that each connecting rod has to be in a predetermined located position for enabling the removal and refitting of its connecting rod big-end cap. Each connecting rod is brought to the desired position for instance by means of an electrical motor which rotatably drives the associated crank shaft through an angle.

It clearly appears from the previous description that the handling, the installing and removal of the connecting rod big-end caps on and from an internal combustion engine are carried out by means of the device according to the invention reliably and quickly. In particular this device may be handled by one single operator who moves the supporting frame and the first movable carriage according to a translatory motion by means of said handles and who will control the energizing or feed of the various hydraulic actuators of this device. The

7 labour and time savings thus achieved are particularly significant and moreover the risks of accidents due to a manual handling of the very heavy connecting rod big-end caps are very reduced.

lt should be understood that the invention is not at all limited to the form of embodiment described and shown which has been given by way of example only. In particular it comprises all the means constituting technical equivalents of the means described as well their combinations if same are carried out according to its gist and used within the scope of the appended claims.

What is claimed is:

l. A device for installing and removing connecting rod big-end caps on and from an internal combustion engine, wherein the improvement consists in that said device comprises:

a supporting frame including means for mounting the same on one side of the engine for horizontal movement along the engine over at least one portion of the length thereof;

a first carriage mounted on said supporting frame and displaceable transversely thereofin a horizontal di' rection perpendicular to the path of travel of said supporting frame;

a second carriage mounted on said first carriage and displaceable thereon in a direction perpendicular to the joint interface plane between said cap and said connecting rod in a predetermined position of the latter;

a toggle system movable in a substantially vertical plane and pivotally connected at one end thereof to said second carriage while comprising at the other end holding means for supporting the connecting rod big-end cap; and

servo-control power means for operating at least said toggle system.

2. A device according to claim 1, wherein said toggle system comprises a pair of linked or pivotally interconnected arms the first one of which is integral at one end thereof with a first toothed segment or sector gear meshing with an idle gear loosely mounted for free rotation on said second carriage and rotatably driven by said servo-control power means, said first arm being pivotally connected at its other end to a splined shaft which is integral with the corresponding end of said second arm, said splined shaft carrying a gear meshing with a second idle gear loosely mounted for free rotation on said first arm, said second idle gear being also in meshing engagement with a second toothed segment or sector gear non-rotatably mounted on said second carriage so that the rotary motion of said servo-control power means is simultaneously conveyed to said first toothed segment integral with said first arm and to said splined shaft integral with said second arm.

3. A device according to claim 2, wherein said servocontrol power means comprises an electrical motor associated with a hydraulic pump, a rotary actuator fitted onto said second carriage and supplied with hydraulic pressure-fluid by said pump, said rotary actuator being associated through a transmission gear train to said idle gear loosely mounted on said second carriage.

4. A device according to claim 1, wherein said mounting means comprises running rollers on said supporting frame engagingly bearing on runways constituted by rails adapted to be secured sidewise to said engine.

5. A device according to claim 1, wherein said first carriage is displaceable on said supporting frame by means of running rollers engagingly bearing on horizontal trackway rails secured onto said supporting frame and extending at right angles to the direction of the path of travel of said supporting frame.

6. A device according to claim 1. wherein said second carriage comprises running side rollers received in runways constituted by apertures provided in the walls of said first carriage and extending in parallel relation to the direction perpendicular to the joint interface plane between said cap and said connecting rod.

7. A device according to claim 1, wherein said second carriage is connected to the piston rod of a hydraulically operated power ram actuator the cylinder of which is pivotally connected to said first carriage.

8. A device according to claim 1, wherein said supporting frame consists ofa pair of braced vertical webs between which is mounted said first carriage.

9. A device according to claim 1, wherein said first carriage consists of a pair of braced vertical plates between which is mounted said second carriage.

10. A device according to claim 2, wherein said first arm consists of a closed box-like casing accommodating said first sector gear and said second idle gear.

11. A device according to claim 2, wherein said second arm comprises a clevis one end of which carries said splined shaft and the other end of which is integral with a supporting member the top face of which has a shape mating in complementary relationship with the bottom face of said connecting rod big-end cap and which includes a pair of parallel cylindrical bores provided on the one hand for receiving tie bolts and corresponding nuts for fastening said cap onto said connecting rod and comprising on the other hand power actuator means for tensioning said tie bolts.

12. A device according to claim 11, wherein each of said tensioning power actuator means comprise a pair of overlying cylindrical hollow pistons through which extends a rod the bottom portion of which is formed with a screw-threaded blind hole adapted to be screwed onto the end of one aforesaid tie bolt and the head of which projecting outwards to the outside of said actuator is screw threaded and connected to a nut bearing upon the outer face of one aforesaid piston.

13. A device according to claim 1, wherein said supporting frame comprises means for positioning and locking same in positions corresponding to the mounting arrangement of said caps onto said connecting rod big-ends whereas said first carriage comprises means for locking it in both of its opposite end positions onto said supporting frame.

14. A device according to claim 1, wherein said supporting frame is movable beyond one end of said engine over a length at least equal to the width of said supporting frame for enabling an operator to load one connecting rod big-end cap onto said toggle system.

15. A device according to claim 1, wherein said servo-control power means are mounted on said supporting frame.

16. A device according to claim 1, wherein said supporting frame and said first carriage comprise handle means for manually moving them according to translatory motions, respectively, along said engine and transversely of said supporting frame.

a a t: a 

1. A device for installing and removing connecting rod big-end caps on and from an internal combustion engine, wherein the improvement consists in that said device comprises: a supporting frame including means for mounting the same on one side of the engine for horizontal movement along the engine over at least one portion of the length thereof; a first carriage mounted on said supporting frame and displaceable transversely thereof in a horizontal direction perpendicular to the path of travel of said supporting frame; a second carriage mounted on said first carriage and displaceable thereon in a direction perpendicular to the joint interface plane between said cap and said connecting rod in a predetermined position of the latter; a toggle system movable in a substantially vertical plane and pivotally connected at one end thereof to said second carriage while comprising at the other end holding means for supporting the connecting rod big-end cap; and servo-control power means for operating at least said toggle system.
 2. A device according to claim 1, wherein said toggle system comprises a pair of linked or pivotally interconnected arms the first onE of which is integral at one end thereof with a first toothed segment or sector gear meshing with an idle gear loosely mounted for free rotation on said second carriage and rotatably driven by said servo-control power means, said first arm being pivotally connected at its other end to a splined shaft which is integral with the corresponding end of said second arm, said splined shaft carrying a gear meshing with a second idle gear loosely mounted for free rotation on said first arm, said second idle gear being also in meshing engagement with a second toothed segment or sector gear non-rotatably mounted on said second carriage so that the rotary motion of said servo-control power means is simultaneously conveyed to said first toothed segment integral with said first arm and to said splined shaft integral with said second arm.
 3. A device according to claim 2, wherein said servo-control power means comprises an electrical motor associated with a hydraulic pump, a rotary actuator fitted onto said second carriage and supplied with hydraulic pressure-fluid by said pump, said rotary actuator being associated through a transmission gear train to said idle gear loosely mounted on said second carriage.
 4. A device according to claim 1, wherein said mounting means comprises running rollers on said supporting frame engagingly bearing on runways constituted by rails adapted to be secured secured sidewise to said engine.
 5. A device according to claim 1, wherein said first carriage is displaceable on said supporting frame by means of running rollers engagingly bearing on horizontal trackway rails secured onto said supporting frame and extending at right angles to the direction of the path of travel of said supporting frame.
 6. A device according to claim 1, wherein said second carriage comprises running side rollers received in runways constituted by apertures provided in the walls of said first carriage and extending in parallel relation to the direction perpendicular to the joint interface plane between said cap and said connecting rod.
 7. A device according to claim 1, wherein said second carriage is connected to the piston rod of a hydraulically operated power ram actuator the cylinder of which is pivotally connected to said first carriage.
 8. A device according to claim 1, wherein said supporting frame consists of a pair of braced vertical webs between which is mounted said first carriage.
 9. A device according to claim 1, wherein said first carriage consists of a pair of braced vertical plates between which is mounted said second carriage.
 10. A device according to claim 2, wherein said first arm consists of a closed box-like casing accommodating said first sector gear and said second idle gear.
 11. A device according to claim 2, wherein said second arm comprises a clevis one end of which carries said splined shaft and the other end of which is integral with a supporting member the top face of which has a shape mating in complementary relationship with the bottom face of said connecting rod big-end cap and which includes a pair of parallel cylindrical bores provided on the one hand for receiving tie bolts and corresponding nuts for fastening said cap onto said connecting rod and comprising on the other hand power actuator means for tensioning said tie bolts.
 12. A device according to claim 11, wherein each of said tensioning power actuator means comprise a pair of overlying cylindrical hollow pistons through which extends a rod the bottom portion of which is formed with a screw-threaded blind hole adapted to be screwed onto the end of one aforesaid tie bolt and the head of which projecting outwards to the outside of said actuator is screw threaded and connected to a nut bearing upon the outer face of one aforesaid piston.
 13. A device according to claim 1, wherein said supporting frame comprises means for positioning and locking same in positions corresponding to the mounting arrangement of said caps onto said connecting rod big-ends whereas said fiRst carriage comprises means for locking it in both of its opposite end positions onto said supporting frame.
 14. A device according to claim 1, wherein said supporting frame is movable beyond one end of said engine over a length at least equal to the width of said supporting frame for enabling an operator to load one connecting rod big-end cap onto said toggle system.
 15. A device according to claim 1, wherein said servo-control power means are mounted on said supporting frame.
 16. A device according to claim 1, wherein said supporting frame and said first carriage comprise handle means for manually moving them according to translatory motions, respectively, along said engine and transversely of said supporting frame. 